FLADE Fan Inner Outer Airfoil Stagger Angle Torque Equalization

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Solution Overview

Problem

Counter-rotating fan aircraft gas turbine engines face challenges in equalizing fan rotor torque and minimizing the number of stator vanes and nozzles, while maintaining efficient operation across varying thrust settings and flight conditions.

Innovation Solution

The design incorporates radially inner and outer airfoils with different stagger angles and a ratio of outer to inner airfoils ranging from 1.5:1 to 4:1, optimizing the FLADE fan assembly for counter-rotating fan engines by eliminating stator vanes and minimizing nozzle count, and modulating bypass flow to achieve efficient operation at various power settings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the inner and outer portions of fladed blades are continuous in section properties at the transition region, then the number of inner blade and outer FLADE fan blades is equal, but the fan rotor torque cannot be equalized between counter-rotatable fans

Engineering Contradiction:

Improveblade continuityVSAvoidtorque equalization

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The fladed blade is segmented into distinct inner and outer portions with different section properties at the transition region, rather than being continuous. This segmentation allows independent optimization of each blade portion to achieve torque equalization between counter-rotatable fans while maintaining manufacturing feasibility through defined transition zones.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different section properties are applied locally at the transition region between inner and outer blade portions. The inner and outer blades have different stagger angles and geometric characteristics in specific regions, allowing localized adjustment of aerodynamic properties to equalize torque without affecting the entire blade structure.

Inventive Principle:

Principle #3Local quality

2Productivity

If stator vanes are included in the fan section, then airflow control is improved, but engine weight increases

Engineering Contradiction:

Improveairflow controlVSAvoidengine weight

Core Design Contradiction:

ProductivityVSWeight of moving object

Solution Approach 1:

Stator vanes are extracted/removed from the fan section of the engine. The design achieves airflow control through the counter-rotating fan configuration and blade geometry alone, eliminating the need for separate stator vane components and thereby reducing engine weight while maintaining operational efficiency.

Inventive Principle:

Principle #2Taking out (Extraction)

3Productivity

If the number of nozzles in the turbine section is increased, then thrust control is improved, but engine weight and complexity increase

Engineering Contradiction:

Improvethrust controlVSAvoidnozzle count

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The turbine nozzles are designed to perform multiple functions: thrust generation, airflow direction control, and potentially variable cycle operation. By making the nozzles multi-functional, the engine achieves improved thrust control capability without increasing the number of separate nozzle components, thereby reducing complexity and weight.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Productivity

If bypass flow is not modulated, then engine structure is simpler, but specific thrust and fuel consumption performance deteriorate at varying power settings

Engineering Contradiction:

Improvespecific thrustVSAvoidbypass flow modulation system

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The bypass flow modulation system incorporates variable geometry components that can dynamically adjust bypass flow characteristics based on engine operating conditions. This dynamic capability allows the engine to optimize specific thrust at takeoff and specific fuel consumption at cruise by varying bypass flow, while the modular design minimizes overall system complexity.

Inventive Principle:

Principle #15Dynamics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration enhances specific thrust at takeoff and reduces specific fuel consumption during cruise, while maintaining constant inlet airflow and minimizing spillage drag, thereby improving engine efficiency and performance across a range of flight conditions.

Implementation Method 1

radially inner and outer airfoils extending radially inwardly and outwardly respectively from a rotatable annular shroud

Methodology Applied

Scientific EffectAerodynamic lift and flow control: Aerofoil

Data Source

PatentUS20100180572A1Flade fan with different inner and outer airfoil stagger angles at a shroud therebetween

Publication Date: 2010.07.22 GENERAL ELECTRIC CO

AI summary

A FLADE fan assembly includes radially inner and outer airfoils extending radially inwardly and outwardly respectively from an annular shroud circumferentially disposed about a centerline. Inner and outer chords extend between inner and outer leading and trailing edges of inner and outer airfoil cross-sections of the radially inner and outer airfoils respectively. Inner and outer stagger angles between the inner and outer chords respectively at the shroud and the centerline are different. The radially outer airfoils may outnumber the radially inner airfoils and particularly by a ratio in a range of 1.5:1 to about 4:1. Load paths or radii may extend radially through the inner and outer airfoils and through the rotating shroud between the inner and outer airfoils and may pass near or through the inner and outer leading edges and through the inner and outer trailing edges.